What does crude oil look like?

Answer 1

Cooking oil that is rancid might have a white color instead of a golden color. The usual way to tell if something like this is rancid is the smell. Rancid cooking oil has a distinct odor. Cooking oil that is not rancid might not have a strong odor. There is also a "best by" date on the bottle to go by.

Answer 2

There is not just one type of crude oil. They various types range from a darkish brown to almost black with a viscosity (thickness) from very low (almost like water) to very high (thicker than ketchup) or even thicker like the La Brea Tar Pits.

The smell differs from a rich hydrocarbon aroma to a sulfidic stink.